1. Field of the Invention
This invention relates to the field of raising, leveling, and supporting existing structures that have become uneven. More particularly, the present invention is a method for raising, leveling, and supporting an existing structural foundation through the use of one or more steel piers which have been driven to a depth adequate to support the structure to be raised.
2. Description of the Related Art
Normal movement, settlement, expansion and contraction of supporting soil may cause a building's structure and its foundation to move, thereby damaging the foundation. Furthermore, excess moisture, such as plumbing leaks, over watered lawns, rainfall and the like, causes uneven movement such as flexing and/or swelling of the foundation resulting in structural and cosmetic damage to the building. The damage may be seen in items such as distorted or broken window frames and panes, sloped flooring, wrinkles in wallpaper and cracked doors, walls, driveways and the like.
Several methods and systems for raising, leveling, supporting and repairing existing damaged foundations are known in the art. One basic method used to achieve an even and stable foundation is to implant pilings directly beneath a slab. In the case of a larger slab it is often necessary for holes to be bored through a building structure's flooring to allow access to the interior beams of the foundation. To support a peripheral or interior beam, the access hole is dug into the earth to a depth typically equal to the length of a support piling and the piling is driven into the ground, one on top of the other, until a certain depth is reached. The building is raised, typically using a hydraulic pump, up to a desired height. By implanting pilings or piers directly beneath the foundation beams, the piers or pilings anchor the foundation by directly supporting the weight of the structure. However, problems have often been encountered with trying to balance the weight of the foundation on the piles or piers.
Many inventions have been dedicated to solving this balancing problem such as the invention described in U.S. Pat. No. 5,288,175 (hereinafter called “the '175 patent”) issued to Knight on Feb. 22, 1994. The '175 patent uses a reinforced segmental precast concrete pile to support the foundation of a structure. Each segment is aligned during installation and continuously reinforces the pile when anchored upon completion.
Another invention focused on providing balance and stability to a building's foundation is shown in U.S. Pat. No. 4,195,487 (hereinafter called “the '487 patent”) issued to Fukushima on Apr. 1, 1980. The '487 patent describes a method of preventing upward movement of foundation pillars in weak ground, where concrete piles are required as the foundation pillars. The concrete piles used in the '175 and '487 patents have given few benefits to re-leveling pre-existing structures and offered many disadvantages.
First, cement piles require very large diameters to reach load-bearing strengths, but driving these pilings into the ground also requires a very large force. Second, cement piles have a greater potential for fracture as they encounter obstructions such as rocks and tree roots on their way into the ground. Third, cement piers take a greater amount of time to utilize especially if a hole is dug first and the piling is constructed in situ.
Further, many inventions using cement piers were not adjustable, though some prior art has utilized complex adjustable anchors. An example of an adjustable pier is seen in U.S. Pat. No. 6,074,133 (hereinafter called “the '133 patent) issued to Kelsey on Jun. 13, 2000. The '133 patent provides for an adjustable foundation piering system in which piers are used to support a building foundation. The adjustable pier is partially encapsulated in the foundation when the foundation is poured. Upon settling of the foundation, the adjustable pier can then be raised. Unfortunately, the '133 piering system is only used to raise and level a foundation as the foundation is being poured which has no benefit to foundations with existing damage.
Inventions utilizing steel piers or pilings were designed to eliminate the difficulties that stemmed from using cement pile or pier structures. U.S. Pat. No. 3,902,326 (hereinafter called “the '326 patent”) issued to Langenbach on Sep. 2, 1975 described a frictionless steel pier system used to stabilize the foundations of settling structures. The steel piers are driven to bedrock or equal load bearing strata and are secured to the foundation to provide unvarying support. However, this frictionless steel pier system heavily depends upon reaching a stable bedrock, which may in some cases be nonexistent. Over time, the frictionless pier system has decreased stability and overall-load bearing capability which allows for denting, bending and potential corrosion of the steel piers.
U.S. Pat. No. 6,684,577 (hereinafter called “the '577 patent”) issued to Dimitrijevic on Feb. 3, 2004 transitioned from the frictionless steel piering system to a support system using H-beams and I-beams being positioned underneath an existing building. A vertically-adjustable cap is then placed in contact with the beams; and a jack is disposed on a lower surface of the cap. The cap is then jacked up until the top end of the jack has pressed an upper surface of the cap against the lower surface of the building foundation. However, the use of such beams as the H-beams has decreased bearing characteristics due to the area of the end of the beam that is driven into the ground is less than that typically used for cement and steel pipe pilings.
The second basic method used to stabilize and support a foundation is to implant a piling or pier adjacent to a slab. An example of this adjacent method is seen in U.S. Pat. No. 6,539,685 (hereinafter called “the '685 patent”) issued to Bell et al on Apr. 1, 2003. The '685 patent provides for an apparatus used to lift and stabilize a foundation including a lifting plate with a pipe section passed over an anchor pier. The anchor pier, located adjacent to the foundation, is secured to the lifting plate using mechanical fasteners. A jack then raises the lifting plate to a position where the foundation is leveled.
Another example of the adjacent method is shown in U.S. Pat. No. 5,154,539 (hereinafter called “the '539 patent”) issued to McCown, Sr. et al. on Oct. 13, 1992. The '539 patent describes the usage of a support bracket extending longitudinally under the foundation, a yoke assembly disposed above the support bracket and a lifting cradle engageable to the bottom surface of the support bracket. A pile driving means is attached to the yoke assembly and is engageable upon a piling to be driven into the ground adjacent to the structure. However, these abovementioned prior art patents having a pier or pile adjacently located to the foundation have historically had problems with stability due to the method of transferring the load of the structure to the piling or pier.
In view of the above described deficiencies associated with the use of conventional methods and systems for raising, leveling, supporting and repairing existing damaged foundations, the present invention has been developed to alleviate these drawbacks and provide further benefits to a user. These enhancements and benefits are described in greater detail herein below with respect to several embodiments of the present invention.